The aim of this experiment was used to investigate the effects of different contents of dietary vitamin D3 on the growth performance and antioxidant and innate immune responses in juvenile black carp Mylopharyngodon piceus. Black carp juveniles were fed six levels of dietary vitamin D3 (VD3) (96, 220, 412, 840, 1480, and 3008 IU/Kg) for 9 weeks. Results showed that highest weight gain (WG) and special growth ratio (SGR) were obtained at 534.2 IU/Kg dietary VD3 according to the second-order polynomial regression model. The protein efficiency ratio (PER) of black carp could be significantly increased by 412, 840, and 1480 IU/Kg dietary VD3 (p < 0.05), while the feed conversion ratio (FCR) were reduced by 412, 840, and 1480 IU/Kg dietary VD3 (p < 0.05). Adequate dietary VD3 content (412, 840, and 1480 IU/Kg) could significantly upregulate expression levels of lipoxygenase 5 (LPO 5); increase the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR); and improve GSH contents and total antioxidant capacities (T-AOC) in the liver of black carp. However, glutathione S-transferase (GST) activities and malondialdehyde (MDA) levels were significantly reduced by adequate dietary VD3 content (412, 840, and 1480 IU/Kg) in the fish liver. In addition, 412, 840, and 1480 IU/Kg dietary VD3 could significantly upregulate the mRNA expression levels of interferon-α (IFN-α), lysozyme (LYZ), hepcidin (HEPC), natural resistance-associated macrophage protein (NRAMP), and complement component 3 (C3) and C9 in the hemocytes and liver of black carp juveniles compared with the VD3-deficient diet (96 IU/Kg). Meanwhile, higher contents of dietary VD3 could increase serum LYZ and ACP activities and C3 and C4 contents in black carp juveniles compared with the groups fed VD3-deficient diet. In conclusion, these results suggest that adequate dietary VD3 could increase growth performances, improve antioxidant capacities, and then enhance innate immune parameters in black carp juveniles.

中文翻译：

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饮食中维生素D3对幼年黑鲤Mylopharyngodon piceus生长性能，抗氧化能力和先天免疫反应的影响。

本实验的目的是研究日粮中维生素D3的含量对少年鲤鱼生长性能以及抗氧化和先天免疫反应的影响。向鱼幼鱼喂食六种水平的饮食维生素D3（VD3）（96、220、412、840、1480和3008 IU / Kg），持续9周。结果表明，根据二阶多项式回归模型，在534.2 IU / Kg日粮VD3下可获得最高的增重（WG）和特殊生长率（SGR）。black鱼的蛋白质效率比（PER）可以显着提高412、840和1480 IU / Kg日粮VD3（p <0.05），而饲料转化率（FCR）则可以降低412、840和1480 IU / Kg日粮VD3（p <0.05）。膳食中的VD3含量足够（412、840，和1480 IU / Kg）可以显着上调脂氧合酶5（LPO 5）的表达水平；增加超氧化物歧化酶（SOD），过氧化氢酶（CAT），谷胱甘肽过氧化物酶（GPX）和谷胱甘肽还原酶（GR）的活性；并改善black鱼肝脏中的GSH含量和总抗氧化能力（T-AOC）。但是，鱼肝中适当的日粮VD3含量（412、840和1480 IU / Kg）显着降低了谷胱甘肽S-转移酶（GST）活性和丙二醛（MDA）水平。此外，412、840和1480 IU / Kg膳食VD3可以显着上调干扰素-α（IFN-α），溶菌酶（LYZ），铁调素（HEPC），天然抗性相关巨噬细胞蛋白（NRAMP）的mRNA表达水平，与缺乏VD3的饮食（96 IU / Kg）相比，黑black幼鱼的血细胞和肝脏中的补体成分3（C3）和C9含量更高。同时，与饲喂缺乏VD3饲料的组相比，较高含量的饲粮VD3可以增加black鱼幼鱼的血清LYZ和ACP活性以及C3和C4含量。总之，这些结果表明，适当的日粮VD3可以提高黑black幼鱼的生长性能，提高抗氧化能力，然后增强其先天免疫参数。